Crystallinity Modulation of Electron Acceptor in One-Photon Excitation Pathway-Based Heterostructure for Visible-Light Photocatalysis

초록

Graphitic carbon nitride is viewed as promising visible-light photocatalyst. However, the high recombination rate of photogenerated carriers within the bulk strongly limits its performance and achieving highly efficient heterostructure remains challenging. Herein, construction of carbon nitride-related heterostructures based on the one-photon excitation pathway (OPEP) mechanism is reported and the complex interplay between component crystallinity and charge transfer kinetics is unraveled. As a proof of concept, prototype TiO2 is selected as the electron-acceptor while crystalline carbon nitride (CCN) is used as the light-absorber. Interestingly, a counter-intuitive phenomenon is found that decreased crystallinity of the electron acceptor is favorable for charge carrier transfer through the heterostructure interface. Detailed structural analysis demonstrates TiO2 with low crystallinity can introduce more dramatic changes to electron distribution of C3N4 than those from highly crystalline counterparts when forming heterostructures, leading to the highly efficient interface. Based on the aforementioned observation, the designed heterostructure (CCN/low-crystalline TiO2) presents a 6 and 4.8 times optimized photocatalytic hydrogen production rate of CCN and CCN/high-crystalline TiO2, respectively. This finding challenges the conventional view and may advance the in-depth understanding for construction of OPEP-related heterostructures and design of highly efficient composite photocatalysts via structure modulation.

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